Schizophrenia is a complex, challenging, and heterogeneous psychiatric condition, affecting up to 0.7% of the world population according to the World Health Organization (WHO, 2006). Patients suffering with schizophrenia present with a range of symptoms, including: positive symptoms, such as delusions, hallucinations, thought disorders, and agitation; negative symptoms, such as mood flatness and lack of pleasure in daily life; cognitive symptoms, such as the decreased ability to understand information and make decisions, difficulty focusing, and decreased working memory function; and sleep disorders.
The etiology of schizophrenia is not fully understood. A major explanatory hypothesis for the pathophysiology of schizophrenia is the Dopamine (DA) hypothesis, which proposes that hyperactivity of DA transmission is responsible for expressed symptoms of the disorder. This hypothesis is based on the observation that drugs effective in treating schizophrenia share the common feature of blocking DA D2 receptors. However, these so-called typical antipsychotics are associated with a very high incidence of extrapyramidal symptoms (EPS). Furthermore, negative symptoms and cognitive impairment are considered relatively unresponsive to typical antipsychotics.
Most currently approved therapies for schizophrenia show efficacy primarily in the management of positive symptoms. An estimated 4.2 million people suffered from schizophrenia in 2012 in the United States and the five major European Union markets. Of those, an estimated 48% experienced predominantly negative symptoms and 80% suffered from cognitive impairment. In addition, about 50% of patients with schizophrenia experience sleep disorders, which can further exacerbate both positive and negative symptoms.
The introduction of the so-called atypical antipsychotics in the last decade represented a significant advance in the treatment of schizophrenia. Although these atypical antipsychotics differ widely in chemical structure and receptor-binding profiles, they share a characteristic of potent antagonism of the Serotonin (5-hydroxytryptamine) type 2 receptor (5-HT2A). A high 5-HT2A:D2 affinity ratio is thought to substantially reduce the liability for inducing EPS, compared with typical antipsychotics.
However, many patients are still treatment-noncompliant despite the advantage of atypical antipsychotics of tolerability. Although the risk of EPS is clearly lower with the atypical antipsychotics, the high doses required with some atypical antipsychotics are likely to result in an increased incidence of EPS and require concomitant medications such as antiparkinson drugs.
In addition to EPS, antipsychotic medications cause a broad spectrum of side effects including sedation, anticholinergic effects, prolactin elevation, orthostatic hypotension, weight gain, altered glucose metabolism, and QTc prolongation. These side effects can affect patients' compliance with their treatment regimen. It should be noted that noncompliance with treatment regimen is a primary reason for relapse of the disease.
Although atypical antipsychotics offer advantages over typical antipsychotics in terms of symptom alleviation and side effect profile, these differences are generally modest. A certain population of patients still remains refractory to all currently available antipsychotics. Newer agents to address these issues continue to be sought.
The disclosure provides compositions, methods, and kits to address this long-felt and unmet need for a treatment for schizophrenia that is effective for all subjects, particularly those who are not effectively treated by currently available therapies. The compositions, methods, and kits of the disclosure lead to greater patient compliance.